The top tier consists of the Oracle Enterprise Manager Grid Control web-based interface. The Grid Control web-based interface is a set of web pages that serve as an interface into the management framework. You can use the Grid Control interface to interact with the Oracle Management Server and the Oracle Enterprise Manager Agents to perform all the functions listed above.

The middle tier is comprised of the Oracle Management Server and the Oracle Management Repository. The Management Server contains a set of software components used to support the Grid Control interface and to interact with the Management Repository. The Management Repository is an Oracle9i database that is used to store the metric information supplied by the Oracle Enterprise Manager Agents.

The Oracle Enterprise Manager Agent, also known as the EMAgent, is the third tier of the management framework. It interacts with the targets and their host systems directly. An EMAgent must exist on every node that houses the entities you want to manage via the Oracle Enterprise Manager management framework.